W83877TF/W83877TG
Publication Release Date: May 2006
-13- Revision 0.7
Multi-Mode Parallel Port, continued
SYMBOL PIN I/O FUNCTION
PD6
16 I/O
24t
PRINTER MODE: PD6
Parallel port data bus bit 6. Refer to the description of the parallel
port for the definition of this pin in ECP and EPP mode.
-
EXTENSION FDD MODE: NC pin
OD
24
EXTENSION. 2FDD MODE:
MOA2
This pin is for Extension FDD A; its function is the same as that
of the
MOA pin.
PD7
17 I/O
24t
PRINTER MODE: PD7
Parallel port data bus bit 7. Refer to the description of the parallel
port for the definition of this pin in ECP and EPP mode.
- EXTENSION FDD MODE: NC pin
OD
24
EXTENSION 2FDD MODE:
DSA2
This pin is for Extension FDD A; its function is the same as that
of the
DSA pin.
4.4 FDC Interface
SYMBOL PIN I/O FUNCTION
WE
85 OD
24
Write enable. An open drain output.
DIR
89 OD
24
Direction of the head step motor. An open drain output.
Logic 1 = outward motion
Logic 0 = inward motion
HEAD
88 OD
24
Head select. This open drain output determines which disk drive
head is active.
Logic 1 = side 0
Logic 0 = side 1
RWC
87 OD
24
Reduced write current. This signal can be used on two-speed
disk drives to select the transfer rate. An open drain output.
Logic 0 = 250 Kb/s
Logic 1 = 500 Kb/s
When bit 5 of CR9 (EN3MODE) is set to high, the three-mode
FDD function is enabled, and the pin will have a different
definition. Refer to the EN3MODE bit in CR9.
WD
86 OD
24
Write data. This logic low open drain writes precompensation
serial data to the selected FDD. An open drain output.
STEP
82 OD
24
Step output pulses. This active low open drain output produces a
pulse to move the head to another track.
